WO2018174194A1 - Optical film, optical film layered body, polarizing plate, and image display device - Google Patents

Abstract

This optical film has a substrate and a phase difference layer provided on and adjacent to the substrate, the phase difference layer being a layer obtained by fixing the vertical orientation of a liquid crystalline compound included in a liquid crystal composition containing a polymer compound and a liquid crystalline compound having a polymerizable group, the difference in the δa value between the polymer compound and the substrate calculated using a three-dimensional SP value being 3 or less, the polymer compound being a polymer having repeating units represented by formula (I), and the content of the polymer compound being 2-10 parts by mass with respect to 100 parts by mass of the liquid crystalline compound. In formula (I) herein, R¹ represents a hydrogen atom or a methyl group, X represents –O- or –NH-, and R² represents a hydrogen agom or an active hydrogen-containing group.

Description

Optical film, optical film laminate, polarizing plate, and image display device

The present invention relates to an optical film, an optical film laminate, a polarizing plate, and an image display device.

The retardation film is generally used as a viewing angle compensation film for a liquid crystal display device or an antireflection film for an organic electroluminescence (hereinafter abbreviated as “EL”) display device.
In recent years, with the widespread use of display devices, it has been required to reduce the thickness of the retardation film used in the display devices and improve the efficiency of manufacturing processes and inspections.
As a method for producing such a retardation film, it is known to form an retardation film after forming an alignment film (intermediate layer) on a substrate.

For example, Patent Document 1 discloses a retardation film having at least a support, an intermediate layer, and a retardation layer in this order, wherein the support is a predetermined cellulose acylate film, and the intermediate layer is A retardation film is described that contains a polyvinyl alcohol resin or an acrylic resin having a polar group, and wherein the retardation layer is a layer in which the homeotropic alignment state of a liquid crystal compound is fixed.

On the other hand, in Patent Document 2, as a homeotropic alignment liquid crystal film that does not require an alignment film, a liquid crystal mixture solution that includes a surfactant, is polymerizable and is reactive on a plastic substrate having a hydrophilic surface. A homeotropic alignment liquid crystal film manufactured by a method for manufacturing a homeotropic alignment liquid crystal film including a step of directly coating is described ([Claim 1] [Claim 10]) and other groups. A method for producing a polarizing film by transferring a homeotropic alignment liquid crystal film produced on a material to a polarizing plate using an adhesive is described ([claim 11] [0071] [FIG. 2]).

JP 2013-235232 A Special table 2008-523443

The inventors have studied Patent Documents 1 and 2, and when the manufacturing process is simplified by omitting the operation of forming an alignment film and the operation of applying a hydrophilic treatment, the alignment state in the retardation layer is low. It has been clarified that there are problems of disorder and insufficient expression of the phase difference in the oblique direction.
In addition, the present inventors examined the transfer method in Patent Document 2, and as a result, the peel strength between the retardation layer (homeotropic alignment liquid crystal film) and another substrate is strong, and there is a problem of causing transfer failure. Clarified that there is.

Accordingly, the present invention provides an optical film and an optical film laminate that have high orientation, excellent transferability, and good oblique retardation, and a polarizing plate and an image display device using the same. Is an issue.

As a result of intensive studies to achieve the above-mentioned problems, the inventors of the present invention have a specific structure satisfying a predetermined SP value relationship with the substrate in the liquid crystal composition before fixing the alignment state of the liquid crystalline compound. The inventors have found that by blending a specific amount of the polymer compound, the orientation is high, the transfer property is excellent, and the development of the retardation in the oblique direction is also good, and the present invention has been completed.
That is, it has been found that the above-described problem can be achieved by the following configuration.

　ここで、式（Ｉ）中、Ｒ^１は、水素原子またはメチル基を表し、Ｘは、－Ｏ－または－ＮＨ－を表し、Ｒ^２は、水素原子または活性水素含有基を表す。 [1] An optical film having a base material and a retardation layer provided adjacent to the base material,
The retardation layer is a layer formed by fixing the vertical alignment of a liquid crystal compound contained in a liquid crystal composition containing a liquid crystal compound having a polymerizable group and a polymer compound,
The difference in δa value between the polymer compound and the substrate, calculated using the three-dimensional SP value, is 3 or less,
The polymer compound is a polymer having a repeating unit represented by the following formula (I):
The optical film whose content of a high molecular compound is 2 mass parts or more and 10 mass parts or less with respect to 100 mass parts of liquid crystalline compounds.

Here, in formula (I), R ¹ represents a hydrogen atom or a methyl group, X represents —O— or —NH—, and R ² represents a hydrogen atom or an active hydrogen-containing group.

[2] The optical film according to [1], wherein the polymer compound is present more on the surface of the retardation layer on the substrate side than on the surface of the retardation layer on the side opposite to the substrate.
[3] The optical film according to [1] or [2], wherein R ² in the formula (I) represents an active hydrogen-containing group, and the active hydrogen-containing group is a hydroxyl group.
[4] The optical film according to [3], wherein the polymer compound has a hydroxyl equivalent per molecule of 100 to 900.
[5] The optical film according to any one of [1] to [4], wherein the liquid crystal composition contains an onium salt compound.
[6] The optical film according to any one of [1] to [5], wherein the content of the boronic acid compound in the liquid crystal composition is less than 0.1 parts by mass with respect to 100 parts by mass of the liquid crystal compound.
[7] The optical film according to any one of [1] to [6], wherein the substrate is a cellulose polymer.
[8] The optical film according to any one of [1] to [7], wherein the δa value of the polymer compound calculated using a three-dimensional SP value is 15 to 19.
[9] The optical film according to any one of [1] to [8], wherein the peel strength between the substrate and the retardation layer is 0.05 to 0.50 N / 25 mm.
[10] The optical film according to any one of [1] to [9], wherein the in-plane retardation of the substrate at a wavelength of 550 nm is 5 nm or less.

[11] The optical film according to any one of [1] to [10] and another film,
An optical film laminate in which another film is bonded to the surface of the optical film opposite to the substrate of the retardation layer via an adhesive or an adhesive.
[12] A polarizing plate having the optical film according to any one of [1] to [10] or the optical film laminate according to [11].
[13] The optical film according to any one of [1] to [10], or the optical film obtained by peeling the substrate from the optical film laminate according to [11], and a polarizer,
A polarizing plate in which a polarizer is bonded to the surface of a retardation layer of an optical film via an adhesive or an adhesive.
[14] The optical film according to any one of [1] to [10], the optical film obtained by removing the substrate from the optical film laminate according to [11], or the description according to [12] or [13] An image display device having a polarizing plate.

According to the present invention, there are provided an optical film and an optical film laminate that have high orientation, excellent transferability, and good oblique phase retardation, and a polarizing plate and an image display device using the same. Can do.

FIG. 1 is a schematic cross-sectional view for explaining an estimation mechanism in the optical film of the present invention.

Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In this specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
Moreover, in this specification, parallel and orthogonal do not mean parallel and orthogonal in a strict sense, but mean a range of ± 5 ° from parallel or orthogonal, respectively.
In the present specification, “(meth) acrylate” is a notation meaning either acrylate or methacrylate, and “(meth) acryl” is a notation meaning either acryl or methacryl, “(Meth) acryloyl” is a notation meaning either acryloyl or methacryloyl.
Further, in the present specification, the liquid crystal composition and the liquid crystal compound include a concept that no longer exhibits liquid crystallinity due to curing or the like.

<Retardation>
In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Unless otherwise specified, the wavelength λ is 550 nm.
In the present invention, Re (λ) and Rth (λ) are values measured at a wavelength λ in AxoScan OPMF-1 (manufactured by Optoscience). By inputting the average refractive index ((Nx + Ny + Nz) / 3) and film thickness (d (μm)) in AxoScan,
Slow axis direction (°)
Re (λ) = R0 (λ)
Rth (λ) = ((Nx + Ny) / 2−Nz) × d is calculated.

　ここで、式（Ｉ）中、Ｒ^１は、水素原子またはメチル基を表し、Ｘは、－Ｏ－または－ＮＨ－を表し、Ｒ^２は、水素原子または活性水素含有基を表す。 [Optical film]
The optical film of the present invention is an optical film having a base material and a retardation layer provided adjacent to the base material.
In the optical film of the present invention, the retardation layer is a layer formed by fixing the vertical alignment of the liquid crystal compound contained in the liquid crystal composition containing the liquid crystal compound having a polymerizable group and the polymer compound. is there.
In the optical film of the present invention, the difference in δa value between the polymer compound and the substrate, calculated using the three-dimensional SP value, is 3 or less.
In the optical film of the present invention, the polymer compound is a polymer having a repeating unit represented by the following formula (I).
Moreover, in the optical film of this invention, content of a high molecular compound is 2 mass parts or more and 10 mass parts or less with respect to 100 mass parts of liquid crystalline compounds.

Here, in formula (I), R ¹ represents a hydrogen atom or a methyl group, X represents —O— or —NH—, and R ² represents a hydrogen atom or an active hydrogen-containing group.

<Δa value>
In the present specification, the δa value is the non-dispersive force of the SP value calculated by the method of Hoy et al. (See VAN KREVELEN, D.W., “PROPERITES OF POLYMERS (ED.3)” ELSEVIER publication (1990)). Intended ingredient.
That is, the δa value can be calculated by the following formula (X) using the three-dimensional SP values (δd, δp, δh) calculated by the method of Hoy et al.
δa = (δp ² + δh ² ) ^0.5 formula (X)
According to the method of Hoy et al., Each value of δd, δp, and δh can be calculated from the chemical structural formula of the desired compound.
In the case of a copolymer composed of a plurality of repeating units, the sum is obtained by multiplying the square value (δd ² , δp ² , δh ² ) of the three-dimensional SP value of each repeating unit by the volume fraction of each repeating unit. By calculating the square value (δd ² , δp ² , δh ² ) of the three-dimensional SP value of the copolymer and substituting it into the above formula (X), the δa value of the copolymer can be obtained.

In the present invention, as described above, the liquid crystal composition before fixing the alignment state of the liquid crystalline compound has a difference in δa value with respect to the substrate of 3 or less, and is represented by the above formula (I). Even when the production process is simplified by blending the polymer compound having a unit at a ratio of 2 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the liquid crystalline compound, the orientation is high, Excellent transferability and good phase difference in the oblique direction.
Although this is not clear in detail, the present inventors presume as follows.
First, FIG. 1 shows a schematic cross-sectional view for explaining an estimation mechanism in the optical film of the present invention.
An optical film 10 shown in FIG. 1 has a base material 1 and a retardation layer 2 provided adjacently on the base material, and the retardation layer 2 has a liquid crystal compound 3 in which the alignment state is fixed, Polymer compound 4 is contained. In addition, in FIG. 1, although the phase difference layer 2 has shown the aspect which contains the liquid crystalline compound 3 formally, after the orientation state of a liquid crystalline compound was originally fixed and became a phase difference layer, The liquid crystal compound need not exhibit liquid crystallinity.
Then, the inventors have a difference in δa value between the polymer compound 4 and the substrate 1 of 3 or less, and the content of the polymer compound 4 having a repeating unit represented by the above formula (I) is as follows: Since the polymer compound 4 tends to be unevenly distributed in the vicinity of the interface with the substrate 1 as shown in FIG. 1 when the amount is 2 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the liquid crystal compound 3, It is speculated that the compound 3 becomes difficult to align in the horizontal direction, and as a result, the alignment in the vertical direction is promoted.
In addition, the orientation can be confirmed by observing the uniformity of the dark field state with an optical microscope, and it is also possible to evaluate the orientation of a region that cannot be determined with the optical microscope by measuring the front contrast.
Hereinafter, various members used in the optical film of the present invention will be described in detail.

〔Base material〕
The base material which the optical film of the present invention has is a base material for supporting a retardation layer described later. For example, a liquid crystal composition is applied when a liquid crystal composition described later is applied to form a retardation layer. The base material used as the object to perform is mentioned. In the present invention, when the substrate is composed of a plurality of layers adjacent to each other, the plurality of layers are collectively defined as a substrate.
Such a substrate is preferably transparent, and specifically has a light transmittance of 80% or more. The term “transparent” means that the visible light transmittance is 60% or more.

Examples of such a substrate include a glass substrate and a polymer film.
Examples of polymer film materials include cellulose polymers such as triacetyl cellulose (TAC), diacetyl cellulose, and cellulose acetate propionate; acrylic polymers such as polymethacrylates and polyacrylates; polycarbonate polymers; polyethylene Polyester polymers such as terephthalate and polyethylene naphthalate; Styrene polymers such as polystyrene and acrylonitrile / styrene copolymers (AS resin); Polyolefin polymers such as polyethylene, polypropylene and ethylene / propylene copolymers; Norbornene polymers; Polymers having an alicyclic structure such as polymers of monocyclic olefins, polymers of cyclic conjugated dienes, vinyl alicyclic hydrocarbon polymers; vinyl chloride type Amide polymers such as nylon and aromatic polyamide; imide polymers; sulfone polymers; polyether sulfone polymers; polyether ether ketone polymers; polyphenylene sulfide polymers; vinylidene chloride polymers; vinyl alcohol polymers; Examples include butyral polymers; arylate polymers; polyoxymethylene polymers; epoxy polymers; or polymers obtained by mixing these polymers.
Among these materials, a cellulose-based polymer or a polymer having an alicyclic structure is preferable, and a cellulose-based polymer is more preferable.

In the present invention, the in-plane retardation of the substrate at a wavelength of 550 nm is preferably 5 nm or less, and more preferably 2 nm or less, because the phase difference before transfer and the efficiency of the bright spot inspection are improved. preferable.

In the present invention, the thickness of the substrate is not particularly limited, but is preferably 5 to 60 μm, and more preferably 5 to 30 μm.

In the present invention, even a polarizer described later may be used as the base material as long as the difference in δa value is 3 or less in relation to a polymer compound described later.

(Retardation layer)
The retardation layer of the optical film of the present invention is a liquid crystal composition containing a liquid crystalline compound having a polymerizable group and a polymer compound (hereinafter also referred to as “liquid crystal composition of the present invention”). This is a layer formed by fixing the vertical alignment of the liquid crystal compound contained therein.
Here, the vertical alignment in the case where the liquid crystal compound is a rod-like liquid crystal compound is also referred to as homeotropic alignment, and the angle formed between the surface of the substrate and the director of the rod-like liquid crystal compound is 70 ° to 90 °. An orientation that falls within the range of 80 ° to 90 ° is preferred, and an orientation that falls within the range of 85 ° to 90 ° is more preferred.
The vertical alignment in the case where the liquid crystalline compound is a discotic liquid crystalline compound means that the angle formed by the surface of the substrate and the disc surface of the discotic liquid crystalline compound is in the range of 70 ° to 90 °. An orientation means an orientation that falls within the range of 80 ° to 90 °, and an orientation that falls within the range of 85 ° to 90 ° is more preferred.

<Liquid crystal compound>
The liquid crystal compound contained in the liquid crystal composition of the present invention is not particularly limited as long as it is a liquid crystal compound having a polymerizable group, and a conventionally known liquid crystal compound can be used.
Here, specific examples of the polymerizable group include an acryloyl group, a methacryloyl group, a vinyl group, a styryl group, and an allyl group, and among them, an acryloyl group or a methacryloyl group is preferable.

In general, liquid crystal compounds can be classified into a rod-shaped type and a disk-shaped type based on their shapes. In addition, there are low and high molecular types, respectively. Polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992).
In the present invention, any liquid crystalline compound can be used, but it is preferable to use a rod-like liquid crystalline compound or a discotic liquid crystalline compound (discotic liquid crystalline compound). Two or more kinds of rod-like liquid crystalline compounds, two or more kinds of disc-like liquid crystalline compounds, or a mixture of a rod-like liquid crystalline compound and a disk-like liquid crystalline compound may be used.
Further, from the viewpoint of fixing the alignment, the liquid crystalline compound preferably has two or more polymerizable groups described above. When the liquid crystal compound is a mixture of two or more, it is preferable that at least one liquid crystal compound has two or more polymerizable groups in one molecule.
As the rod-like liquid crystal compound, for example, those described in claim 1 of JP-T-11-53019 and paragraphs [0026] to [0098] of JP-A-2005-289980 can be preferably used. As the tick liquid crystalline compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732 and paragraphs [0013] to [0108] of JP-A-2010-244038 are preferably used. However, it is not limited to these.

In the present invention, it is preferable to use a rod-like liquid crystalline compound as the liquid crystalline compound. For example, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoates, cyclohexanecarboxylic acid phenyl esters, cyano Phenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

　ここで、式（Ｉ）中、Ｒ^１は、水素原子またはメチル基を表し、Ｘは、－Ｏ－または－ＮＨ－を表し、Ｒ^２は、水素原子または活性水素含有基を表す。 <Polymer compound>
The polymer compound contained in the liquid crystal composition of the present invention has a δa value at which the difference from the δa value of the base material described above (referring to the absolute value of the difference, hereinafter the same) is 3 or less, and It is a polymer having a repeating unit represented by the following formula (I).
The polymer may be a homopolymer having only a repeating unit represented by the following formula (I) as long as the polymer has a repeating unit represented by the following formula (I). A copolymer having the repeating unit represented by the formula (I) and other repeating units may be used.

Here, in formula (I), R ¹ represents a hydrogen atom or a methyl group, X represents —O— or —NH—, and R ² represents a hydrogen atom or an active hydrogen-containing group.

In the present invention, since the polymer compound can be uniformly present at the above-mentioned substrate interface and the surface shape of the retardation layer can be improved, the polymer compound has a difference from the δa value of the substrate. A polymer having a δa value of 0.1 to 2.0 is preferable, a polymer having a δa value of 0.2 to 1.5 is more preferable, and a difference of 0.3 is preferable. More preferably, the polymer has a δa value of ˜1.0.

In the present invention, the polymer compound is preferably a polymer having a δa value of 13 to 19, and the δa value of 15 to 19 because the effect of improving the orientation according to the present invention is increased. More preferred are the polymers shown.

Such a polymer compound is preferably a polymer having a repeating unit represented by the above formula (I) and wherein R ² in the above formula (I) represents an active hydrogen group-containing group.
Specific examples of the active hydrogen-containing group include a hydroxyl group, a carboxy group, an amino group, an amide group, a sulfo group, a mercapto group, and an imino group. Of these, a hydroxyl group is preferable.

In the present invention, when an active hydrogen-containing group represented by R ² in the above formula (I) has a hydroxyl group, the hydroxyl group equivalent per molecule of the polymer compound is 100 to 900 because the orientation is further improved. Preferably, 300 to 600 is more preferable.

In the present invention, when the polymer compound having a repeating unit represented by the above formula (I) has a hydroxyl group as an active hydrogen-containing group represented by R ² in the above formula (I), the above formula (I) The content of the represented repeating unit is preferably 3 to 50 mol%, more preferably 5 to 30 mol%, based on all repeating units of the polymer compound.
Further, when the polymer compound having a repeating unit represented by the above formula (I) has a hydroxyl group as an active hydrogen-containing group represented by R ² in the above formula (I), it is represented by the above formula (I). The δa value of the repeating unit is preferably 13 to 25, and more preferably 17 to 21.

In the present invention, it is preferable that the polymer compound does not have a fluorine atom because the orientation is further improved.

In the present invention, when the above-mentioned base material has a δa value of 10 or more, particularly 13 to 19, the above-mentioned polymer compound is a three-dimensional SP because the effect of improving the orientation according to the present invention is increased. A polymer having a repeating unit having a δa value calculated from the value of 13 or more and less than 18 is preferred.
Examples of the monomer constituting such a repeating unit include methyl methacrylate (δa = 13.8), methoxyethyl acrylate (δa = 13.7), 2-acetoacetoxyethyl methacrylate (δa = 15.2), and , Tetrahydrofurfuryl acrylate (δa = 13.2) and the like, and these may be used alone or in combination of two or more. It should be noted that the δa value in parentheses attached to the monomer is the δa value of the repeating unit composed of the monomer. In addition, the content of repeating units composed of these monomers is preferably 30 to 100 mol%, more preferably 50 to 80 mol%, based on all repeating units of the polymer compound.

In the present invention, when the above-mentioned base material has a δa value of 5 or more and less than 10, especially 7 or less and less than 10, the polymer compound is A polymer having a repeating unit having a δa value calculated using a three-dimensional SP value of 5 or more and less than 11 is preferred.
Examples of the monomer constituting such a repeating unit include octadecyl acrylate (δa = 6.3), lauryl acrylate (δa = 7.4), cyclohexyl acrylate (δa = 10.2), dicyclopentanyl acrylate. -To (δa = 9.6), isobornyl acrylate (δa = 10.4), and the like. These may be used alone or in combination of two or more. It should be noted that the δa value in parentheses attached to the monomer is the δa value of the repeating unit composed of the monomer.
In addition, the content of repeating units composed of these monomers is preferably 30 to 95 mol%, more preferably 50 to 85 mol%, based on all repeating units of the polymer compound.

Examples of the polymer compound having a repeating unit represented by the above formula (I) include polymer compounds represented by the following formulas A101 to A108, A111 to A124, A201 to A209, and A301 to A307. It is done.
In the following description, a polymer compound represented by the following formula A101 is referred to as “polymer compound A101”. In addition, polymer compounds represented by the following formulas A102 to A108, A111 to A123, A201 to A209, and A301 to A307 are also expressed in the same manner.

The weight average molecular weight of such a polymer compound is not particularly limited, but is preferably 1,000 to 500,000, more preferably 2,000 to 100,000, and still more preferably 3,000 to 50,000.
Here, the weight average molecular weight of the polymer compound is defined as a polystyrene equivalent value by GPC (gel permeation chromatography) measurement. The weight average molecular weight of the polymer compound is, for example, HLC-8120 (manufactured by Tosoh Corporation), TSKgelMultiporeHXL-M (Tosoh Corporation, 7.8 mm ID × 30.0 cm) as a column, and THF (tetrahydrofuran) or NMP (NMP as an eluent). -Methylpyrrolidone).

In the present invention, the content of the polymer compound is 2 parts by mass or more and 10 parts by mass or less and preferably 2 parts by mass or more and less than 10 parts by mass with respect to 100 parts by mass of the liquid crystalline compound described above. The amount is more preferably 3 parts by mass or more and 8 parts by mass or less, and further preferably 4 to 6 parts by mass.

In the present invention, for the reason that the orientation is higher, the above polymer compound is a surface on the substrate side in the retardation layer (interface on the substrate side) than the surface on the opposite side of the substrate in the retardation layer. More specifically, it is preferable to exist more in the retardation layer than the polymer compound existing in the thickness region of 0.2 μm from the surface opposite to the substrate in the retardation layer. It is preferable that the amount of the polymer compound present in a thickness region of 0.2 μm from the surface (interface on the base material side) is larger.
Here, the degree of uneven distribution of the polymer compound in the retardation layer can be measured by time-of-flight secondary ion mass spectrometry (TOF-SIMS).

<Onium salt compound>
The liquid crystal composition of the present invention preferably contains an onium salt compound when the above-described polymer compound has a hydrophilic group, for the reason that the alignment becomes higher.
As the onium salt compound, a known onium compound can be used as a vertical alignment agent. Specific examples include compounds described in paragraphs [0042] to [0052] of JP-A-2016-105127.
When the onium salt compound is contained, the content is preferably 0.5 to 5 parts by mass, and more preferably 1 to 3 parts by mass with respect to 100 parts by mass of the liquid crystal compound described above.

<Boronic acid compound>
In the liquid crystal composition of the present invention, the release property of the formed retardation layer from the base material becomes good and the transferability becomes better. The amount is preferably less than 0.1 parts by mass with respect to 100 parts by mass, and more preferably does not contain a boronic acid compound.
In addition, as a boronic acid compound, a well-known onium compound is mentioned as a vertical alignment agent. Specific examples include the compounds described in paragraphs [0053] to [0054] of JP-A-2016-105127.

<Polymerization initiator>
The liquid crystal composition of the present invention preferably contains a polymerization initiator.
The polymerization initiator to be used is preferably a photopolymerization initiator capable of initiating a polymerization reaction by ultraviolet irradiation.
Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatics, and the like. Group acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US patent) No. 3549367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,221,970), acylphosphine Oxide compounds (Japanese Patent Publication No. 6) No. 3-40799, JP-B-5-29234, JP-A-10-95788, JP-A-10-29997) and the like.

<Polymerizable monomer>
The liquid crystal composition of the present invention may contain a polymerizable monomer in terms of the uniformity of the coating film and the strength of the retardation layer.
Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the above-mentioned polymerizable group-containing discotic liquid crystalline compound. Examples thereof include those described in paragraph numbers [0018] to [0020] in JP-A No. 2002-296423.
The addition amount of the polymerizable monomer is preferably 1 to 50% by mass and more preferably 5 to 30% by mass with respect to the discotic liquid crystalline compound.

<Surfactant>
The liquid crystal composition of the present invention may contain a surfactant in terms of the uniformity of the coating film and the strength of the retardation layer.
Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specifically, for example, compounds described in paragraphs [0028] to [0056] in JP-A No. 2001-330725, and paragraphs [0069] to [0126] in Japanese Patent Application No. 2003-295212 are described. And the compounds described.

<Solvent>
The liquid crystal composition of the present invention preferably contains a solvent from the viewpoint of workability and the like for forming the retardation layer.
Specific examples of the solvent include ketones (eg, acetone, 2-butanone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (eg, dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (eg, hexane) ), Alicyclic hydrocarbons (eg, cyclohexane, etc.), aromatic hydrocarbons (eg, toluene, xylene, trimethylbenzene, etc.), halogenated carbons (eg, dichloromethane, dichloroethane, dichlorobenzene, chlorotoluene, etc.) ), Esters (eg, methyl acetate, ethyl acetate, butyl acetate, etc.), water, alcohols (eg, ethanol, isopropanol, butanol, cyclohexanol, etc.), cellosolves (eg, methyl cellosolve, ethyl cellosolve, etc.), cello Rubacetates, sulfoxides (for example, dimethyl sulfoxide, etc.), amides (for example, dimethylformamide, dimethylacetamide, etc.), etc. may be used, and these may be used alone or in combination of two or more. Good.

<Method for forming retardation layer>
In the present invention, examples of the method for forming the retardation layer include a method in which the above-described liquid crystal composition is applied on the above-described substrate to obtain a desired alignment state and then fixed by polymerization.
Examples of the application method of the liquid crystal composition include a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.
The polymerization conditions are not particularly limited, but it is preferable to use ultraviolet rays in polymerization by light irradiation. The irradiation amount is preferably 10 mJ / cm ² to 50 J / cm ² , more preferably 20 mJ / cm ² to 5 J / cm ² , and still more preferably 30 mJ / cm ² to 3 J / cm ^2. 50 to 1000 mJ / cm ² is particularly preferable. Moreover, in order to accelerate | stimulate a polymerization reaction, you may implement on heating conditions.

The thickness of the retardation layer of the optical film of the present invention is not particularly limited, but is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.

The optical film of the present invention preferably has a peel strength between the substrate and the retardation layer of 0.05 to 0.50 N / 25 mm for the reason that transferability is better, and is 0.10 to 0. More preferably, it is 20 N / 25 mm.

[Optical film laminate]
The optical film laminate of the present invention has the above-described optical film of the present invention and another film, and the other film has a pressure-sensitive adhesive or a surface on the surface opposite to the substrate of the retardation layer of the optical film. It is a laminated body bonded through an adhesive.

[Other films]
The other film which the optical film laminated body of this invention has is not specifically limited, The polymer film illustrated as a base material which the optical film of this invention mentioned above has is mentioned. Moreover, the film which horizontally aligned the liquid crystalline compound is also mentioned.
In these polymer films and films in which liquid crystal compounds are horizontally aligned, a λ / 4 plate having an in-plane retardation of 1/4 of the incident light source wavelength can be used as another film. In this case, by offsetting the retardation in the thickness direction of the film on which other films are laminated and adjusting it to near 0 nm, the optical characteristics such as color when viewed from an oblique direction as well as the front are improved. It becomes possible to do.
In the present invention, the thickness of the other film is not particularly limited, but is preferably 5 to 60 μm, and more preferably 5 to 30 μm.

[Adhesive or adhesive]
The pressure-sensitive adhesive or adhesive used for pasting the optical film of the present invention described above with another film is not particularly limited, but after the pasting, a change in force (adhesive strength) stuck even after a certain time has passed. Since it is small and can be peeled off as necessary, it is preferable to use an adhesive.
Examples of the adhesive include rubber adhesives, (meth) acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinyl pyrrolidone adhesives, poly Examples include acrylamide-based adhesives and cellulose-based adhesives.
Among these, acrylic adhesives (pressure sensitive adhesives) are preferable from the viewpoints of transparency, weather resistance, heat resistance, and the like.

[Polarizer]
The polarizing plate of this invention is a polarizing plate which has the optical film or optical film laminated body of this invention mentioned above.
Moreover, the polarizing plate of this invention has a polarizer, when the base material mentioned above does not serve as a polarizer.

When the polarizing plate of the present invention has a polarizer separately from the substrate, the polarizer is bonded to the surface of the retardation layer contained in the optical film of the present invention via an adhesive or an adhesive. It is preferable.
When the polarizing plate of the present invention uses the above-described optical film laminate, the polarizer peels the substrate from the optical film laminate, and the pressure-sensitive adhesive or adhesive is exposed on the surface of the exposed retardation layer. It is preferable that it is bonded via.
Here, examples of the pressure-sensitive adhesive or adhesive used when laminating the polarizer include the same as those described in the optical film laminate of the present invention described above.

[Polarizer]
The polarizer which the polarizing plate of this invention has is not specifically limited if it is a member which has a function which converts light into specific linearly polarized light, A conventionally well-known absorption type polarizer and reflection type polarizer can be utilized. .
As the absorption polarizer, an iodine polarizer, a dye polarizer using a dichroic dye, a polyene polarizer, and the like are used. Iodine polarizers and dye polarizers include coating polarizers and stretchable polarizers, both of which can be applied. Polarized light produced by adsorbing iodine or dichroic dye to polyvinyl alcohol and stretching. A child is preferred.
In addition, as a method for obtaining a polarizer by stretching and dyeing in the state of a laminated film in which a polyvinyl alcohol layer is formed on a substrate, Patent No. 5048120, Patent No. 5143918, Patent No. 5048120, Patent No. 4691205, Japanese Patent No. 4751481, and Japanese Patent No. 4751486 can be cited, and known techniques relating to these polarizers can also be preferably used.
As the reflective polarizer, a polarizer in which thin films having different birefringence are stacked, a wire grid polarizer, a polarizer in which a cholesteric liquid crystal having a selective reflection region and a quarter wavelength plate are combined, or the like is used.
Among them, a polyvinyl alcohol resin (a polymer containing —CH ₂ —CHOH— as a repeating unit, particularly at least one selected from the group consisting of polyvinyl alcohol and an ethylene-vinyl alcohol copolymer, in terms of better adhesion. Are preferably included.

In the present invention, the thickness of the polarizer is not particularly limited, but is preferably 3 μm to 60 μm, more preferably 5 μm to 30 μm, and even more preferably 5 μm to 15 μm.

[Image display device]
The image display device of the present invention is an image display device having the optical film of the present invention or the polarizing plate of the present invention.
The display element used for the image display device of the present invention is not particularly limited, and examples thereof include a liquid crystal cell, an organic EL display panel, a plasma display panel, and the like.
Among these, a liquid crystal cell and an organic EL display panel are preferable. That is, the image display device of the present invention is preferably a liquid crystal display device using a liquid crystal cell as a display element and an organic EL display device using an organic EL display panel as a display element.

[Liquid Crystal Display]
The liquid crystal display device which is an example of the image display device of the present invention is a liquid crystal display device having the above-described polarizing plate of the present invention and a liquid crystal cell.
In the present invention, among the polarizing plates provided on both sides of the liquid crystal cell, the polarizing plate of the present invention is preferably used as the polarizing plate on the front side, and the polarizing plate of the present invention is used as the polarizing plate on the front side and the rear side. Is more preferable.
Below, the liquid crystal cell which comprises a liquid crystal display device is explained in full detail.

<Liquid crystal cell>
The liquid crystal cell used in the liquid crystal display device is preferably in a VA (Virtual Alignment) mode, an OCB (Optically Compensated Bend) mode, an IPS (In-Plane-Switching) mode, or a TN (Twisted Nematic). It is not limited to.
In a TN mode liquid crystal cell, rod-like liquid crystal molecules are substantially horizontally aligned when no voltage is applied, and are twisted and aligned at 60 to 120 °. The TN mode liquid crystal cell is most frequently used as a color TFT liquid crystal display device, and is described in many documents.
In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied. The VA mode liquid crystal cell includes: (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of tech. Papers (Preliminary Proceed) 28 (1997) 845 in which the VA mode is converted into a multi-domain (MVA mode) for widening the viewing angle. ), (3) A liquid crystal cell (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary collections 58-59 of the Japan Liquid Crystal Society) (1998)) and (4) SURVIVAL mode liquid crystal cells (announced at LCD International 98). Further, any of a PVA (Patterned Vertical Alignment) type, a photo-alignment type (Optical Alignment), and a PSA (Polymer-Stained Alignment) may be used. Details of these modes are described in JP-A-2006-215326 and JP-T 2008-538819.
In an IPS mode liquid crystal cell, rod-like liquid crystal molecules are aligned substantially parallel to the substrate, and the liquid crystal molecules respond in a planar manner when an electric field parallel to the substrate surface is applied. The IPS mode displays black when no electric field is applied, and the absorption axes of the pair of upper and lower polarizing plates are orthogonal. JP-A-10-54982, JP-A-11-202323, and JP-A-9-292522 are methods for reducing leakage light during black display in an oblique direction and improving the viewing angle using an optical compensation sheet. No. 11-133408, No. 11-305217, No. 10-307291, and the like.

[Organic EL display device]
As an organic EL display device which is an example of the image display device of the present invention, for example, from the viewing side, the polarizing plate of the present invention and a plate having a λ / 4 function (hereinafter also referred to as “λ / 4 plate”). The aspect which has an organic electroluminescent display panel in this order is mentioned suitably.
Here, the “plate having a λ / 4 function” refers to a plate having a function of converting linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). For example, a λ / 4 plate Specific examples of the embodiment in which is a single layer structure include a stretched polymer film, a retardation film provided with an optically anisotropic film having a λ / 4 function on a support, and the like. As an aspect in which the four plates have a multilayer structure, specifically, there is a broadband λ / 4 plate formed by laminating a λ / 4 plate and a λ / 2 plate.
The organic EL display panel is a display panel configured using an organic EL element in which an organic light emitting layer (organic electroluminescence layer) is sandwiched between electrodes (between a cathode and an anode). The configuration of the organic EL display panel is not particularly limited, and a known configuration is adopted.

Hereinafter, the features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Example 1]
<Production of optical film>
On TAC1 (cellulose polymer film; TG40 manufactured by Fuji Film Co., Ltd.), the liquid crystal composition 1 having the composition shown below was applied with a # 3.5 wire bar.
Subsequently, it heated for 60 second with a 40 degreeC warm air for drying of the solvent of a composition, and orientation ripening of a liquid crystalline compound.
Subsequently, ultraviolet irradiation (300 mJ / cm ² ) was performed at 40 ° C. with an oxygen concentration of 100 ppm under a nitrogen purge to fix the orientation of the liquid crystal compound to form a retardation layer, and the optical film of Example 1 was produced.

―――――――――――――――――――――――――――――――――
Composition of Liquid Crystal Composition 1 ―――――――――――――――――――――――――――――――――
The following rod-like liquid crystalline compound (M-1) 83 parts by mass The following rod-like liquid crystalline compound (M-2) 15 parts by mass The following rod-like liquid crystalline compound (M-3) 2 parts by mass The following polymerizable monomer (M-4) 8 parts by mass Part polymerization initiator (Irgacure 127, manufactured by BASF) 2 parts polymerization initiator (Irgacure OXE01, manufactured by BASF) 4 parts by mass The following fluoropolymer (M-5) 0.4 parts by mass The following fluoropolymer (M-6) 0.3 parts by mass The following onium compound S01 2 parts by mass The above polymer compound A107 5 parts by mass Toluene 621 parts by mass Methyl ethyl ketone 69 parts by mass ――――――――――――――――――――― ―――――――――――

Rod-like liquid crystalline compound (M-1)

Rod-like liquid crystalline compound (M-2)

Rod-like liquid crystalline compound (M-3)

Polymerizable monomer (M-4)

Fluoropolymer (M-5)

Fluoropolymer (M-6)

Onium salt compound S01

The prepared optical film was analyzed by etching TOF-SIMS (Time-of-Flight Secondary Mass Spectrometry) analysis, and almost all of the added polymer compound A107 was unevenly distributed at the interface between TAC1 as the base material and the retardation layer. I confirmed that

[Examples 2 to 6, Comparative Examples 1 to 3]
The same as Example 1 except that the type and amount of polymer compound in liquid crystal composition 1, the amount of onium salt compound S01, and the amount of boronic acid compound were changed to the types and amounts shown in Table 1 below. The optical film was produced by the method.
In addition, the boronic acid compound mix | blended in Example 3 and 4 used the following boronic acid compound S2.

[Example 7]
A liquid crystal composition 2 having the following composition was prepared.
―――――――――――――――――――――――――――――――――
Composition of Liquid Crystal Composition 2 ―――――――――――――――――――――――――――――――――
The rod-like liquid crystalline compound (M-1) 83 parts by mass The rod-like liquid crystalline compound (M-2) 15 parts by mass The rod-like liquid crystalline compound (M-3) 2 parts by mass The polymerizable monomer (M-4) 8 parts by mass Partial polymerization initiator (Irgacure 907, manufactured by BASF) 4 parts by mass The above fluoropolymer (M-5) 0.4 parts by mass The following fluoropolymer (M-7) 0.3 parts by mass The above onium compound S01 2 parts by mass Polymer Compound A302 5 parts by mass Acetone 577 parts by mass 1-methoxy-2-propyl acetate 102 parts by mass ―――――――――――――――――――――――――――― ―――――

Fluoropolymer (M-7)

An optical film was produced in the same manner as in Example 1 except that COP1 (Arton film manufactured by JSR) was used instead of TAC1, and liquid crystal composition 2 was used instead of liquid crystal composition 1.

[Comparative Example 4]
As the liquid crystal composition 2, an optical film was produced in the same manner as in Example 7 except that the type and amount of the polymer compound were changed to the types and amounts shown in Table 1 below.

[Evaluation]
(1) Orientation Using a polarizing microscope in a crossed Nicols condition, insert each optical film produced on the stage and rotate the stage so that the slow axis of the substrate is parallel to the analyzer or polarizer of the polarizing microscope .
When the optical film was observed in this state, a uniform dark field observed for an area of 98% or more was evaluated as “S” as having excellent orientation, and an area of 95% or more and less than 98% was evaluated. A case where a uniform dark field was observed was evaluated as “A” as having excellent orientation, and a case where a uniform dark field was observed for an area of 80% or more and less than 95% was regarded as being slightly inferior in orientation. “B” was evaluated, and those in which a uniform dark field was observed for an area of less than 80% were evaluated as “C” as being poor in orientation. The results are shown in Table 1 below.

(2) Diagonal retardation The base material is peeled off for each optical film produced, and the exposed surface of the retardation layer is attached to a glass substrate without optical anisotropy via an adhesive (SK1478, manufactured by Soken Chemical Co., Ltd.). The thickness direction retardation Rth (550) at a wavelength of 550 nm was measured using AxoScan OPMF-1 (manufactured by Optoscience). The results are shown in Table 1 below.
In Table 1 below, the in-plane retardation Re (550) at a wavelength of 550 nm is also described.

(3) Peel strength After the produced optical film was cut into 150 mm × 25 mm, the base material was peeled off, and the exposed surface of the retardation layer was stuck on a glass substrate via an adhesive (SK1478, manufactured by Soken Chemical Co., Ltd.). Combined. At this time, only the 80 mm × 25 mm portion was bonded to the glass substrate. The adhesive strength was measured with a Tensilon universal material tester (Orientec Co., Ltd.) when the unbonded part was gripped and peeled by applying a force in the 180 ° direction. Along with the measurement results, the evaluation results based on the following criteria are shown in Table 1 below.
<Evaluation criteria>
A: 0.10 N / 25 mm or more and 0.20 N / 25 mm or less B: 0.05 N / 25 mm or more and less than 0.10 N / 25 mm or more than 0.20 N / 25 mm and 0.50 N / 25 mm or less C: 0. More than 50N / 25mm or less than 0.05N / 25mm

From the results shown in Table 1, when the difference in δa value between the polymer compound and the substrate is larger than 3, the dark field area is reduced by observation with a polarizing microscope because of the defect in the orientation (vertical orientation). Okay (Comparative Examples 1 and 4).
In addition, when the blending amount of the polymer compound is less than 2 parts by mass or more than 10 parts by mass with respect to 100 parts by mass of the liquid crystalline compound, there is a defect in the orientation (vertical alignment). It was found that the area of the dark field was reduced and the expression of the phase difference (Rth) in the oblique direction was also small (Comparative Examples 2 and 3).

On the other hand, the difference in δa value between the polymer compound and the substrate is 3 or less, and the blending amount of the polymer compound is 2 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the liquid crystalline compound. It was found that the dark field was observed over almost the entire surface by observation with a polarizing microscope, so that the orientation (vertical orientation) was excellent, and an oblique phase difference (Rth) was developed (Examples 1 to 4). 7).

[Example 11]
A cycloolefin polymer film (Arton film, Re = 95 nm, Rth = 100 nm, film thickness: 20 μm, manufactured by JSR Corporation) was attached to the retardation layer of the optical film produced in Example 1 with an adhesive, Then, TAC1 which is a base material was peeled and the optical film was produced.

[Examples 12 to 17 and Comparative Example 11]
An optical film was produced in the same manner as in Example 11 except that the optical film produced in Examples 2 to 7 and Comparative Example 1 was used in place of the optical film produced in Example 1.

[Evaluation]
A roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an MD (Machine Direction) direction in an aqueous iodine solution and dried to obtain a polarizer (polarizing film) having a thickness of 20 μm. A polarizer in which a cellulose triacetate film TD80UL was bonded to one surface of the polarizer as a polarizer protective film subjected to alkali saponification as described above was produced.
A polarizing plate was produced by adhering the retardation layer side of the optical films produced in Examples 12 to 17 and Comparative Example 11 to the polarizer on which TD80UL was not attached via an adhesive layer. At this time, they were bonded so that the slow axis of the cycloolefin polymer film and the transmission axis of the polarizer were parallel.

For the produced liquid crystal display device, according to paragraph [0109] of JP-A-2015-25830, the polarizing plate is measured by placing another polarizer on the side on which the optical film is attached and rotating it. The brightness of black display (L0) and white display (L7) was measured using a measuring instrument (BM-5A, manufactured by TOPCON), and the front contrast (L7 / L0) [hereinafter abbreviated as “CR”. ] Was calculated. The results were evaluated in the following three grades A to C. The results are shown in Table 2 below.
A evaluation: CR> 100,000,
B evaluation: CR> 50,000 <CR ≦ 100,000
C evaluation: CR ≦ 50,000

DESCRIPTION OF SYMBOLS 1 Base material 2 Retardation layer 3 Liquid crystalline compound 4 Polymer compound 10 Optical film

Claims (14)

An optical film having a base material and a retardation layer provided adjacent to the base material,
The retardation layer is a layer formed by fixing the vertical alignment of the liquid crystal compound contained in a liquid crystal composition containing a liquid crystal compound having a polymerizable group and a polymer compound,
The difference in δa value between the polymer compound and the substrate, calculated using a three-dimensional SP value, is 3 or less,
The polymer compound is a polymer having a repeating unit represented by the following formula (I):
The optical film whose content of the said high molecular compound is 2 mass parts or more and 10 mass parts or less with respect to 100 mass parts of said liquid crystalline compounds.

Here, in formula (I), R ¹ represents a hydrogen atom or a methyl group, X represents —O— or —NH—, and R ² represents a hydrogen atom or an active hydrogen-containing group. 2. The optical film according to claim 1, wherein the polymer compound is present more on the surface of the retardation layer on the side of the substrate than on the surface of the retardation layer on the side opposite to the substrate. The optical film according to claim 1, wherein R ² in the formula (I) represents an active hydrogen-containing group, and the active hydrogen-containing group is a hydroxyl group. The optical film according to claim 3, wherein the polymer compound has a hydroxyl group equivalent of 100 to 900 per molecule. 5. The optical film according to claim 1, wherein the liquid crystal composition contains an onium salt compound. 6. The optical film according to claim 1, wherein the content of the boronic acid compound in the liquid crystal composition is less than 0.1 parts by mass with respect to 100 parts by mass of the liquid crystal compound. The optical film according to any one of claims 1 to 6, wherein the substrate is a cellulose polymer. The optical film according to any one of claims 1 to 7, wherein a δa value of the polymer compound calculated using a three-dimensional SP value is 15 to 19. The optical film according to any one of claims 1 to 8, wherein a peel strength between the substrate and the retardation layer is 0.05 to 0.50 N / 25 mm. The optical film according to any one of claims 1 to 9, wherein the substrate has an in-plane retardation at a wavelength of 550 nm of 5 nm or less. The optical film according to any one of claims 1 to 10 and another film,
The optical film laminate, wherein the other film is bonded to the surface of the optical film opposite to the base material of the retardation layer via an adhesive or an adhesive. A polarizing plate having the optical film according to any one of claims 1 to 10 or the optical film laminate according to claim 11. The optical film according to any one of claims 1 to 10, or the optical film obtained by peeling the substrate from the optical film laminate according to claim 11, and a polarizer,
The polarizing plate by which the said polarizer is bonded to the surface of the phase difference layer which the said optical film has via an adhesive or an adhesive agent. The optical film according to any one of claims 1 to 10, the optical film obtained by removing the substrate from the optical film laminate according to claim 11, or the polarizing plate according to claim 12 or 13. , Image display device.

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